Behavior Change and Sexually Transmitted Incidence in Relation to PREP Use Among Men Who Have Sex with Men in Kenya.

We measured change in sexual practices and the incidence of C. trachomatis (CT) and N. gonorrhoeae (NG) within a prospective cohort of Kenyan MSM taking PrEP in Kenya. Over the one year of study participation, CT and NG were diagnosed in urine at baseline, 6- and 12- months. Multivariable Cox regression identified factors associated with incident infection. Sexual practices were assessed at baseline and every 3 months. We evaluated changes over time and in relation to PrEP adherence via generalized estimating equation analysis. From October 2017-January 2018, 158 participants initiated PrEP, having 10.3% baseline CT/NG prevalence (either or both). The incidence was 17.2 cases per 100 person-years (95% CI 11.7-25.5). Incident CT/NG increased with report of: transactional male sex partner (adjusted Hazard Ratio (aHR) = 2.46, p = 0.016, z = 2.40), regular female sex partner (aHR = 2.22, p = 0.051, z = 1.96), greater social support (highest vs. lowest quartile, aHR = 6.24, p = 0.012, z = 2.51), and CT/NG infection prior to enrollment (aHR = 2.90, p = 0.002, z = 3.03). Multiple sex partners, condomless sex, and transactional sex decreased over time and were not associated with PrEP adherence. Urethral CT/NG incidence remained high and there was no evidence of PrEP-related behavioral change. There is need for ongoing etiologic testing, improved understanding of risk from female sex partners, and development of more effective risk reduction interventions.